The present invention relates generally to crossbar switching configurations and more particularly to a linearly expandable self-routing crossbar switch and associated method. The invention is applicable in any multi-source/multi-destination digital switching application including the fields of computer networking and digital telecommunications switching.
A number of different applications present the need for a switching arrangement which may be configured for routing a flow of data from a particular port to any one of a number of other ports which are connected with the switching arrangement. In the prior art, such switching arrangements are generally referred to as crossbar switches. FIG. 1 illustrates a four-port prior art crossbar switch, generally indicated by the reference numeral 10, which is capable providing a data flow path between two selected ones of any of four ports A, B, C or D. While the arrangement of FIG. 1 has proven to be effective for its intended use, it should also be appreciated that its capability for expansion is extremely limited.
FIG. 2 illustrates an overall crossbar switching arrangement, which is generally referred to by the reference numeral 20, that is made up of four of the crossbar switching arrangements 10a-d originally shown in FIG. 1. Arrangement 20 is configured for providing a data flow path between two selected ones of any of eight data ports A through H. While arrangement 20 serves its intended purpose, it should be appreciated that in order to double the number of ports served using the prior art four-port crossbar switch 10 of FIG. 1, the number of four-port crossbar switches 10 is multiplied by a factor of four.
As another example which is not illustrated, if sixteen ports (again doubling the number of ports) are to be served the number of prior art four-port crossbar switches would increase to sixteen. Thus, one of ordinary skill in the art should recognize that increasing the number of ports served results in a geometric increase in the required number of individual four-port cross-bar switches. This geometric expansion is particularly disadvantageous in terms of the hardware costs associated with expansion. Of course, a geometric expansion in terms of hardware results in a corresponding decrease in reliability of the overall switching arrangement. Another disadvantage stems from the fact that each additional layer of switches added to the overall arrangement adds latency (i.e., decreased data throughput based on time delays) in data routing operations.
The present invention solves the foregoing problems by providing a highly advantageous cross-bar switching arrangement which is expandable in a linear manner. An associated method is also provided.